Neuro 2 final Flashcards
Where are globular bushy cells located?
posterior ventral nucleus
Where are spherical bushy cells located?
anterior nucleus
What do bushy cells relay?
frequency
What is the ratio of bushy cells to hair cells in the cochlea?
1:1
Where are octopus cells located?
dorsal/ventral cochlear nuclei
What do octopus cells detect?
interval between frequencies
SPECIFICALLY ONSET AND DURATION
Where do octopus cells send axons?
anterior nucleus of the LL
Multipolar cells send information about?
intensity
the superior olive detects what?
localization of sound and intensity differences from side to side
time lag is
interaural time
localizing sound in space; comparing one side to the other
interaural time is the responsibility of what structure?
SO
The medial SO has what cells?
bipolar
the medial SO detects
time lag
the medial SO detects frequencies best
< 3 KHz
signals from the ipsilateral side are
excitatory
signals from the contralateral side are
inhibitory
Where does the medial SO receive axons from?
anterior ventral cochlear nucleus (bilateral)
What does the lateral SO detect
differences in intensity
the lateral So works best at what frequency?
> 2-3 KHz
What nuclei does the IC have
central, pericentral, external
the LL goes to what nucleus in the IC?
central
Some axons from the LL don’t make it to the ipsilateral central nucleus of the IC, where do they go?
cross to the other side via the posterior commissure of probst
the go to contralateral central nucleus of the IC or posterior nucleus of the LL
The axons from the posterior nucleus of the LL have what neurotransmitter?
GABA
Where does the central nucleus of the IC recieve axons from?
LL
Where do the axons from the central nucleus of IC go?
anterior part of MG via brachium of IC
Where does the MG send signals to?
area 41 (specific thalamic nucleus)
What are the 2 main functions of the central nucleus?
- interaural time
2. some intensity of sound
What responds to intesity of sound?
- multipolar cells
- SO lateral
- central nucleus of the IC
T or F
pericentral and external nuclei are non-specific?
T
What is the pericentral pathway?
pericentral—->area 42——>back to superior colliculus
The axons returning to the deep SC allow participation in what>?
orientation reflex
the deep SC send what tracts to participate in the orientation reflex?
tectospinal
(neck mm)
tectomesencephalic/tectopontine
(extrinsic eye mm)
what is the pathway of the external nucleus of the IC?
external nucleus of IC—–>medial MG (large)—–>area 42
Neurons of the MG respond to what?
combinations of frequency (not individual)
time intervals between frequencies (speech)
Where does the anterior MG receive from?
central nucleus of the IC
Where does the medial MG receive from?
external nucleus of IC &
SPINAL CORD AND DCNs DIRECTLY
Where does the posterior MG receive from?
pericentral nucleus
Area 41 is broken into what?
isofrequency columns
area 41 responds to
timing and frequency
What is the pathway of area 41/42?
area 41/42—–>area 22—->area 39/40——>area 44/45 (Broca’s= area 44)
T or F
Area 41 is made of slabs of cells with concurrent function.
F
alternating
The second letter in the isofrequency column refers to….
ipsillateral side (sometimes inhibitory)
The first letter in the isofrequency column refers to….
contralateral side (always excitatory)
If Broca’s area is destroyed, what happens?
you can hear and understand, but are unable to articulate anything in order to respond
Wernicke’s area is responsible for?
semantic speech
What happens if Wernicke’s is destroyed?
everything sounds like gibberish
What layer of the retina converts to electrical signal?
layer 2
What makes up the outer layer of the eye?
sclera and cornea
What makes up the middle layer of the eye?
choroid + ciliary body/mm + iris
What layer of the retina is the furthest back?
1
Where are photoreceptors found?
layer 2
What is the area in layer 2 where photoreceptors are concentrated?
macula
Where are the cell bodies for the photoreceptors found?
layer 4
Where is light focused at in the retina?
fovea
The fovea is made entirely of
cones
The center of the fovea is known as
foveola
After the light goes to layer 2, it then travels to where?
ganglion cells of layer 8
The ganglion cells of layer 8 then send to
CN II
Where does CN 2 exit the eye?
optic disk
T or F
there are photoreceptors in the optic disk.
F
Layer 1 of the retina is known as
pigment epithelium
Layer 1 function
prevents light from scattering; also stores vitamin A
Layer 2 contains ________; which are specialized endings of _________
photoreceptors; dendrites
rods detect ______
cones detect _______
rods- black and white
cones- color
T or F cones work better in low light situations.
F
Rods and cones operate on the basis of
receptive fields
T or F
As you move away from the fovea cone concentration increases.
F
What is used for peripheral vision?
rods
What is used for night vision?
rods
What pigment do rods contain?
rhodopsin
What do rods release in the abscence of light?
glutamate
T or F
Glutamate released from the rods is inhibitory.
T
What increases when in the dark?
cGMP increases causing a Na+ influx
this causes a release of glutamate turning the bipolar cell off
How is glutamate released in the dark?
tonically
What happens when light hits rods?
activates Rhodopsin——>break down cGMP—-> decrease Na+——->decrease glutamate—–>bipolar is on
Cones are described as _______cells
photopic
What do long-wavelength cones detect?
red
What do medium-wavelength cones detect?
green
What do short-wavelength cones detect?
blue
What is deuteranopia?
green-blind—–brown/gray apperance
What is Deuteranomaly?
green-defiecient——must be bright for detection
What is achromatic vision?
colorblindness
What is the ratio of rods to ganglion cells?
10:1
What is the ratio of cones to ganglion cells?
1:1
What layer mediates these connections?
layer 6
Layer 6 is made up of what cells?
horizontal/amacrine
Horizontal cells detect what?
changes between dark and light
Amacrine cells detect?
change in the change from dark to light
Ganglion cells are found in
layer 8
How many ganglion cells per side are there?
900K- 1.2 Million
Where is the optic disk located?
15 degrees nasal to the fovea
Why dont we notice this in our visual field?
Gestalt closure principle——-filling escatoma
What are the types of ganglion cells?
- M (y)
- P (x)
- W
What type of ganglion cell does not use a center surround fashion?
W
M (y) ganglion cells recieve mostly from?
rods
M (y) cells detect
movement and contrast
M (y) are large cells and only do
black/white
P (x) receive from ________and detect
cones; color
P (x) have _______ receptor fields
small
W ganglion cells have slow conduction and go to the
SC and pre-tectal nucleus
W cells respond to
general images of light/dark
T or F
Upper/Lower visual fields swap, so images are projected upside down on the retina.
T
The upper visual field projects where?
lower LG
The upper visual field loops around ________, this is called what?
the temporal lobe,
meyer’s loop
Where does the lower visual field project?
dorsal LG
How much of the visual cortex does the macular visual field occupy?
50%
Where do all visual fields project?
layer IV of area 17
Where is the primary visual cortex most concentrated?
calcarine fissure
How many layers make up the LG?
6
Which layers of the LG are magnocellular?
1 and 2
Where do layers 1 and 2 receive from, and what do they detect?
receive from M (y);
movement and contrast
What layers are parvicellular? Where do they receive from?
layers 3-6;
P (x)
What do layers 3-6 detect?
detail, color, and shape
T or F
In the LG the layers receive either ipsilateal or contralateral ganglion cells, there is an alternating pattern.
T
What is area 17 AKA?
striate cortex
What is the bright white band of axons in layer 4 of area 17 called?
band of Gennari
T or F
Receptive fields in the LG are oval shaped and stellates in layer 4 have their own receptive fields.
F
round receptive fields
The stellates in layer 4 of area 17 have this kind of receptive field.
elongated receptive fields with center-surround
T or F
There is a 1:1 ratio of LG axons to cortical cells.
F
a convergence of many LG axons to a cortical cell
Cortical receptive fields respond to ______ of light.
bars
What do these bars end up representing?
a single continuous shape by connecting the contour of the bars of light
What are the alternating pattern of contra/ipsi parts known as in area 17?
ocular dominance columns
What is the only termination point of the LG in the cortex?
layer 4 of area 17
The other layers of area 17 receive from where?
layer 4 of area 17
What is found perpindicular to the ocular dominance columns?
orientation columns
which cells have the elongated fields?
orientation columns
What are the cells of the orientation columns known as?
simple cells
Moving away from layer 4 the cells become _______
complex cells (layers 2,3,5,6)
Describe complex cells receptive fields.
A convergence of the fields from layer 4
What do complex cells lose because of the convergence of fields?
center-surround
T or F
Complex cells are orientation specific and pick up movement/direction.
T
What are blobs?
clusters of cells between the columns; primarily respond to color.
Where do blobs receive from?
LG
Do blobs have on/off capability?
no
Are blobs layer-specific?
no
T or F
Areas 18/19 are made of simple, complex, and hypercomplex cells.
F
no simple cells
How many pathways leave area 17?
2 streams of the visual cortical pathway
What are the two streams of the visual cortical pathway?
Dorsal pathway (parietal) Ventral pathway (temporal)
Where does the parietal stream terminate?
posterior parietal area (7a)
What does the dorsal stream receive signals from and what do they detect?
M (y) ganglion cells;
motion, contrast, and localization
Which stream deals with where something is and if it is moving?
dorsal
Where do signals pass through to get to the PPA?
mid-temporal area
Where does the temporal stream terminate?
inferior temporal area (37)
Where does the ventral stream receive signals and what do they deal with?
P (x) ganglion
form/shape +color/detail
What is achromotopsia?
a form of colorblindness;
trouble with interpretaion of colors; everything is gray
What is prosopagnosia?
loss of ability to recognize form (area 17)
inability to recognize people by their face/ only physical features
What are the two ocular movements for visual tracking?
saccades + smooth pursuit
What are saccades?
sudden jerking movement of the eyes
What is the purpose of saccades?
to bring objects into the fovea for focus
can do up to 700 degrees per second
What is smooth pursuit?
following a moving object
How fast does smooth pursuit track?
30 degrees a second (much slower)
Which ocular movement involves the vestibular apparatus?
smooth pursuit
What does PPRF stand for?
paramedian pontine reticular formation
What is the PPRF’s function?
horizontal gaze center
What activates the PPRF?
the SC
If the ipsilateral lateral rectus muscle contracts, what must the contra do?
relax
What happens during staring?
SNr shuts of the SC; which in turn shuts down the PPRF so no visual tracking occurs
Does the SC normally have the SC tonically inhibited?
yes, until ready to visual track something
What is the island of reil?
insula;
island of neocortical tissue formed by deep invagination of the lateral fissure
